In the monitoring settings, you can define global values regarding scanning intervals, unusual and similar sensors detection, auto-discovery, and uptime threshold.

If you use PRTG on premises and open the system administration page from another administration page, PRTG will ask you to enter your credentials again for security reasons if 15 minutes (900 seconds) have passed since your last credential-based login. A dialog box will appear. Enter your Login Name and Password for PRTG in the corresponding fields and confirm to continue.

Monitoring Settings

This documentation refers to the PRTG System Administrator user accessing the PRTG web interface on a master node. If you use other user accounts, interfaces, or nodes, you might not see all of the options in the way described here. If you use a cluster installation, note that failover nodes are read-only by default.

Scanning Intervals

This option is not available in PRTG hosted by Paessler.

Available Intervals

Define the intervals available in the dropdown list of every object's settings. In the text field, enter one value in each line. Use s, m, h, and d for defining seconds, minutes, hours, and days. By default, there are the following scanning intervals defined:

30s: 30 seconds

1m: 1 minute

5m: 5 minutes

10m: 10 minutes

15m: 15 minutes

30m: 30 minutes

1h: 1 hour

4h: 4 hours

6h: 6 hours

12h: 12 hours

1d: 1 day

We recommend that you do not use intervals shorter than 10 seconds to prevent system overload. Intervals below 10 seconds are not officially supported! The maximum supported scanning interval is 10 days.

You can also define specific points in time to indicate when PRTG executes scanning actions. Enter up to 50 concrete UTC points in time according to the formula

The unusual detection can set sensors to an Unusualstatus when there are values that are untypical for the time span in which they are measured. PRTG compares the current average values to the historic monitoring results for this purpose. If the current values show a big difference to the values that are normally retrieved by a sensor, this sensor will indicate this with the unusual status.

You can define the granularity of the unusual detection here (this means, how big the difference must be to cause an unusual status). If you disable the unusual detection (both settings to Never), sensors will never show an unusual status.

You can enable and disable unusual detection for specific devices, entire groups, and probes in the respective Object Settings.

Unusual detection requires sensor data from at least four weeks (28 to 34 days) to have enough data available for comparison. If there is less data available, the unusual status cannot be calculated.

Show Unusual When

Define when a sensor shows the unusual status, comparing the weekday. If you enable the detection here, the average of the values that were measured on the day before is compared to the average of the same weekday in previous weeks. Choose between:

Never: Disable unusual detection for weekday average.

24h average is <80% or >120% of weekday average: The average of the values measured on the day before is either lower than 80% or higher than 120% than usually on the same weekday.

24h average is <50% or >200% of weekday average: The average of the values measured on the day before is either lower than 50% or higher than 200% than usually on the same weekday.

24h average is <20% or >500% of weekday average (recommended): The average of the values measured on the day before is either lower than 20% or higher than 500% than usually on the same weekday.

24h average is <10% or >1,000% of weekday average: The average of the values measured on the day before is either lower than 10% or higher than 1,000% than usually on the same weekday.

24h average is <1% or >10,000% of weekday average: The average of the values measured on the day before is either lower than 1% or higher than 10,000% than usually on the same weekday.

For example, consider a traffic sensor that usually measures 100 MB average traffic on a weekday. If you choose the first option, it would show an unusual status if the average from the day before is below 80 MB or above 120 MB.

Show Unusual When

Define when a sensor shows the unusual status, comparing the hour-of-day. If you enable the detection here, the average of the values that were measured in the hour before is compared to the average of the same hour on the same weekday in previous weeks. Choose between:

Never: Disable unusual detection for hour-of-day average.

Hourly average is <80% or >120% of hour-of-day average: The average of the values measured in the hour before is either lower than 80% or higher than 120% than usually in this hour of this weekday.

Hourly average is <50% or >200% of hour-of-day average: The average of the values measured in the hour before is either lower than 50% or higher than 200% than usually in this hour of this weekday.

Hourly average is <20% or >500% of hour-of-day average (recommended): The average of the values measured in the hour before is either lower than 20% or higher than 500% than usually in this hour of this weekday.

Hourly average is <10% or >1,000% of hour-of-day average: The average of the values measured in the hour before is either lower than 10% or higher than 1,000% than usually in this hour of this weekday.

Hourly average is <1% or >10,000% of hour-of-day average: The average of the values measured in the hour before is either lower than 1% or higher than 10,000% than usually in this hour of this weekday.

Consider a traffic sensor that usually measures 10 MB average traffic within an hour. If you choose the first option, it would show an unusual status if the average from the hour before is below 8 MB or above 12 MB.

Logging

Define if unusual events will be written to the logfile. Choose between:

Do not log unusual events

Write unusual events to the log (default)

Similar Sensors Detection

Similar sensors detection enables PRTG to analyze sensor data for similarities. The detection will run in the background with low priority. The recommended setting for similar sensors detection is to let PRTG automatically decide how many channels will be analyzed. However, you can also override this setting.

When similar sensors analysis is turned off or if you have exceeded 1,000 sensors and have chosen the automatic analysis depth option, the similar sensors entry will not be shown in the main menu bar.

Analysis Depth

Define the number of channels PRTG will analyze to detect similarities between sensors or turn the analysis off. Choose between:

Manage automatically based on sensor count (recommended): The analysis depth depends on the total number of sensors you have configured. PRTG will analyze all channels for up to 500 sensors, and only the primary sensor channels for up to 1,000 sensors. If exceeding 1,000 sensors, the analysis will be turned off. This is the default setting in PRTG on premises.

Analyze primary channels only: Only the primary channels of sensors are analyzed. Be aware of potentially high CPU load of PRTG when choosing this setting for more than 1,000 sensors.

Analyze all channels (higher CPU load): Similarity detection is applied to all channels. Be aware of potentially high CPU load of PRTG when choosing this setting for more than 500 sensors.

Turn analysis off: No similarity detection takes place. Choose this option if you are not interested in the analysis results or you want to keep the CPU load of PRTG at a minimum. This is the default setting in PRTG hosted by Paessler.

Recommended Sensors Detection

With the sensor recommendation engine, PRTG can analyze devices in your network and suggest sensors that are still missing for a complete monitoring. The analysis runs with low priority in the background when you add a new device, when the last analysis was executed more than 30 days ago, or when you manually start it.

Manage automatically based on sensor count (recommended): PRTG runs the detection engine for installations with up to 5,000 sensors by default. If you exceed this threshold, PRTG disables the detection engine for performance reasons. We recommend that you set this option so you do not miss any important monitoring data about your network, without risking to run into performance issues.

Always show recommendations: PRTG always analyzes your devices even if your installation exceeds 5,000 sensors and you will never miss any suggestion to complete your monitoring. If you enable this option, please keep this setting in mind in case you encounter performance issues.

Turn recommendations off: PRTG never recommends sensors. Select this option if you have performance issues with PRTG or if you do not want to see this information on device overview tabs. Moreover, you will not find the option Recommend Now in device context menus or on overview tabs anymore.

Auto-Discovery

Run Discovery At

Define the time when PRTG automatically runs an Auto-Discovery in your network if you configured a daily or weekly Discovery Schedule in the auto-discovery group settings. Choose a full hour between 0:00 and 23:00. We recommend that you choose a time when there is little user activity in your network because auto-discoveries can produce a certain amount of load.

Uptime Threshold

Desired Minimum Uptime

Define which uptime in percent PRTG regards as 100 percent. This setting affects the colors shown next to the sensor icons in reports. Select one of the predefined values between 90 % and 99.999 %.

Save your settings. If you change tabs or use the main menu, all changes to the settings will be lost!

More

Knowledge Base: How can I speed up PRTG—especially for large installations?